Get A Contact Support Error When Trying To Purchase Anything

Have you already tried a hard reset? All you have to do is hold the power button on the console until it turns off (it should only take about 10 seconds). After that, turn it back on and try again.

If it still doesn't work, then I'd suggest try again on Xbox.com.

Hi! I recommend instead of immediately contacting xbox support (https://beta.support.xbox.com).
You can do it via chat or phone and you'll see that you'll immediately solve the problem without wasting time!

If issues persist, it may be wise to actually call support on the off chance you do need them: https://beta.support.xbox.com/contact-us

Try contact official xbox support through here: http://support.xbox.com/contact-us

Sorry to hear you're experiencing this issue. Check
https://account.microsoft.com to make sure all your billing info is correct and up to date. You can try phone support if you like but they may send you to your bank if you're having trouble with your bank card. The number for phone support in North America
is 1-800-469-9269 or you can click the link already provided.